Nothing is what it seems at Willcox Playa

August 8, 2010.Charlie O'Brien and I arrived at Willcox Playa around ten thirty and the temperature was already climbing into the upper nineties. On the flat salt pan, there is not much shade. The white sand reflects the sun and seems to double its intensity. Looking for bugs, we spent a lot of time close to the radiantly hot ground. Cooling off in the air-conditioned car between stops kept us going.


A dirt road parallels the tracks of the Union Pacific Railroad. We followed along with a shipment of huge windmill blades going to California. Far ahead, water was rushing. Across the road? We could see it churning and spilling down from the higher eastern embankment. Charlie and I couldn't quite agree where it was coming from. It seemed to be spouting out of a huge pipeline. But the closer we got, the smaller the stream of water became. Finally, there was no water crossing the road at all. All we found was a muddy pool of standing water on the west side of the road. Everything else, a mirage.




Those temporary pools of murky rainwater were full of life. Little pulsating openings turned out to be the mouths of big golden tadpoles, floating up-side-down while skimming debris off the surface and probably gulping air into their developing lungs. Just when my brain had formed the search image 'tadpole' I realized that some of the creatures had oddly segmented tails. Tadpole Shrimp (Triops sp.)! Dormant eggs had been hidden in the dry sand since the last flood maybe a year or two ago. The recent rains made them hatch and the little crustaceans developed within days in warm standing water. They have to race through their whole life cycle and produce new eggs before the temporary desert ponds dry out again. They have done this in nearly unchanged form for the last 70 million years and are considered the oldest animal species on earth. I had read about these predatory living fossils, but I had no idea that they would be so big (about 3 cm).

Metallic green insects, nearly invisible in the glare of sun on white sand, were running and flying like wasps or flies along the water's edge. I didn't fall for that deception: Tiger Beetles were my main interest on this trip.We caught 4 species but we saw many more. They had the wind on their side: it kept blowing any that flew up out of reach across the water. Some additional species came to the black light at night at Twin Lakes. We'll have to return for the other 70 or so species.

















The rains had also triggered many wild flower seeds to sprout. The dominant plant, a purple-blooming nightshade, seemed to be already covered in reddish berries (most likely poisonous). Or were they Lady Bugs? They turned out to be the larvae of Ten-lined Potato Beetles, Leptinotarsa decemlineata. I assume that they can advertise their presence with their contrasting colors because they are as indigestible to predators as their alkaloid-loaded host plant. Their similarity to bad tasting Lady Bugs may enhance the protection (Müllerian mimicry)



At closer inspection, some of the narrow, silvery buds of the nightshade turned out to be beetles that fit exactly in color, shape and even venation: Epicauta tricostata (above and below, left). These are blister beetles, with chemical defenses of their own and probably rather safe, even if their cover is blown.
But some of the beetles were just harmless imitators: False Blister Beetles, Oedemeridae (above, right). The silvery white color of both beetle species is of course not just cryptic or deceptive: like the surface of the silvery leaves of the nightshades, it serves as sun protection.


Something was running on the ground between the wide-spaced grasses. It looked nearly like a fairly big spider and certainly acted like one. So at first I hesitated to reach for it, just long enough to let it get away. Then, of course, we caught it in a container. It turned out to be another Meloid, Negalius mamoratus (all Meloid ids by John Pinto). This one was dark, but an air cushion under slightly inflated elytra seemed to efficiently protect it from overheating by radiation.


There is a narrow range of optimal temperatures for any ectotherm, active organisms. We noticed later that these beetles climb up into higher grasses to sleep as soon as it gets to cool to keep the running-spider illusion going.

























At Twin Lakes, a bare, round sandy spot of several feet diameter with an off-center entrance hole seemed to indicate a Harvester Ant nest. After some painful experiences, I approach those only carefully. But I always check around them for Anteater Scarabs, genus Chremastocheilus. So far without luck, so that will be another story. This time the entrance hole, while in the right location of the arena, was quite small and very round. Only a single hymenopteran was working, a harvester-ant-mimicking Ammophila wasp (A. formicoides or A. wrightii. thanks, Eric Eaton for the id options). She slipped inside, grabbed an 'armful' of sand, moved all the way to the outside of the flat area to drop her load on an inconspicuous slope, and immediately returned for more. She kept using the same dump site and her times inside the hole kept getting longer and longer as she dug deeper. Eventually she'll catch and paralyze a caterpillar, drag it into her hole, lay an egg on it and seal the chamber. Her larva will develop inside the living, paralyzed host until she pupates and then hatches as another winged huntress.


We moved on to the dunes of Blue Sky Road. By now it was afternoon and a thunderstorm over the Chiricahuas sent chilling blasts of wind into the Playa and the sun dissapeared behind clouds. All around the dayactive insects were retiring. A beetle in the genus Rhipiphoris nearly had me believe that he was a wasp - with his long clear wings, reduced elytra, imitation of a hymenopteran waist, and huge shiny eyes, and the way he was clinging to a dry stick just like a sleepy wasp in the evening .




























A small fuzzy Clerid, Enoclerus analis (ID Jaques Rifkind), hanging on a blade of dry grass, and a dusk active Carabid, Panagaeus relative Micrixys distincta (Haldeman), running on the ground, gave both convincing imitations of female velvet ants that are famous for their painful sting.



On a Cholla Cactus several weevils of the species Gerstaeckeria unicolor were clinging to the tufts of glochids where they were nearly invisible, except to a weevil expert like Charlie who knows exactly where to look.


A round, moving dot in the sand could have been a tumbling seed or maybe a spider, but the little hairy Tenebrionid Edrotes arens did not at all look like a beetle.


Finally Charlie scared up a very pretty Checkered Garter Snake, Thamnophis marcianus. These shy reptiles usually just glide away as fast as possible. Instead, this one tried to intimidate us by taking the defensive stance of a rattler.


Mimicry, warning colors, cryptic shapes and behaviors, camouflage colors and patterns, and protective behaviors are used by animals of all habitats. Just check out the page from an old German Lexicon. But at Willcox Playa, deception seems to be the rule. There, due to a complete lack of cover, everyone has to hide in plain sight.

Springtime Blister Beetles of the Southwest

After a year of severe drought, record heat, and parched desert landscapes, this year's spring rains brought us glorious carpets of annual flowers all over the Southwest. Yet, according to my records beginning in 2007, there still seem to be much fewer insects than usually in March and April. The reason may lay in the prolonged drought or just the cool night temperatures that we are currently enjoying...

However, the large stands of Lupines, Desert Chicory, and Brittle Bush have attracted a multitude of colorful beetles of a family that is superbly adapted to our desert environments: The Blister Beetles or Meloids.

Blister Beetles occur all over the world except in New Zealand and Antarctica. Of the 335 US species the majority lives in the Southwest. We also have the most bizzare and colorful ones right here in our deserts.

This month, you'll see them everywhere where there are plenty of fresh flower petals to eat.




At Saguaro National Park West you may come across
aggregations of Iron Cross Beetles Tegrodera aloga (right) wandering along the path in the morning or hanging suspended from weed stalks during the hotter part of the day.
















Big Master Blister Beetles Lytta magister weigh down the Brittle Bush Flowers in our backyard in Picture Rocks.







Identification
A Blister Beetle is recognizable by his big square head, narrow pronotum, an elongated soft body, long legs (Tarsal formula 5-5-4) and thread-like or beaded antennae.

Meloid Poison
The bright and striking color combinations of many Meloid species are probably a warning to predators: Blister Beetles are poisonous. Their blood and soft tissues contain Cantharidin. The chemical is produced by the male, transferred to the female during mating, and can also be found in the body of the larva. Blister beetles respond to disturbances by reflex bleeding from knee-joints and other body parts.

Skin contact with this fluid can raise painful blisters.
Grazing animals like horses can suffer digestive and urinary tract damage, inner hemorrhages and even death if they are unlucky enough to ingest too many beetles with their feed. Epicauta vittata and Epicauta occidentalis reportedly cause the most damage. They are not among our spring species but occur during the summer months. The lethal dose for an adult horse is more than 150 beetles. Horse owners here in Arizona are keeping a weary eye on grasshopper population explosions because they are usually closely followed by Epicauta  mass occurrences. (Epicauta larvae feast on grasshopper eggs).  Current alfalfa harvesting techniques involving waltzing the plants before baling sometimes trap hundreds of the beetles in hay bales. Alfalfa harvesting methods that avoid crushing the beetles and letting them instead escape before the hay is baled are available and are currently researched at the University of Colorado.


In folk medicine of many cultures extracts from Blister Beetles have been used for their presumed potency as an aphrodisiac and are still in use a remedy against warts.



















Red-eared Blister Beetle Lytta auriculata (left) and metallic green Lytta stygica (right) devour Lupine and Cream-cup flowers in Catalina State Park




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Red and black banded Elegant Blister Beetles Eupompha elegans pose openly on white Desert Chicory flowers in Sabino Canyon.




The big flight-less Oil Beetles Meloe barbarus hide in shady spots on a cow pastures of Picture Rocks. They hide so well actually, that the female I found is only the 5th AZ state record since the species was described.
read more about the amzing life cycle here: http://thesmallermajority.com/2012/10/08/life-saving-beetles/














Inflated Beetles Cysteodemus armatus carry insulating air pockets under their wings. They are at home mainly in the Mojave and the Colorado Desert but they have been found as far east as the White Tank Mountains close to Phoenix. (I went looking for them last weekend - no luck - so this photo is by Phillip Ruttenbur, copyright 2005)









Phillip Kline (copyright 2010) found this beautiful Pleuropasta mirabilis in Arivaipa Canyon in Pinal County and sent me the picture for identification. He graciously allowed me to add it to this blog.














Dull orange beetles of the genus Nemognatha love the thick pink heads of New Mexico Thistles. Their elongated maxillae form a sucking tube that allows them to compete with bees for the nectar. On the flower heads they also find mates and lay their eggs.










Life Cycle
While the adults are vegetarians, Meloid larvae are predatory or parasitoid. The females of several Meloid genera position their eggs on flowers. Highly mobile, long-legged larvae emerge and hitch a ride on a visiting bee to get to its nest. From the BugGuide: 'In at least one Meloe species, the larvae climb to the top of a grass or weed stalk as a group, clump together in the shape of a female solitary ground bee, exude a scent that is the same as, or closely resembles, the pheromones of the female bee, and wait for a male ground bee to come along. When he does, he tries to mate with the clump of larvae, whereupon they individually clamp onto his hairs. He then flies away, finds and mates with one or several real female bees, and the larvae transfer to the female(s) and with them to the bee's nest.' There the larvae change into short-legged grubs that consume the bee off-spring as well as the pollen and nectar provisions. The winter diapause is spent in form of legless coarctate larvae which in early spring change again into short-legged but mouthless creatures only to prepare the pupal chambers. There they pupate and the adult beetles hatch ready for the next spring flower season to start the cycle over. This highly complex cycle is called a hypermetamorphosis.

A-triungulin; B-caraboid stage; C-coarctate larva;D-scarabaeidoid stage; E-pupa
F-adult beetle (imago) of a Striped Blister Beeltle, Epicauta vittata

The best is yet to come
Here in Arizona, the monsoon rains will trigger another burst of fresh vegetation in summer, and with it many new species of Meloids will emerge, mostly in the genera Epicauta and Pyrota.Three species of the genus Pyrota that we'll find again in Arizona from July to October.